<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .InputAddOn {
            display: flex;
        }

        .InputAddOn-field {
            flex: 0.5;
        }
    </style>
</head>

<body>
    <p>我们常常需要在输入框的前方添加提示，后方添加按钮。</p>
    <div class="InputAddOn">
        <span class="InputAddOn-item">Amount</span>
        <input class="InputAddOn-field">
        <button class="InputAddOn-item">...</button>
    </div>
</body>

</html>